funny enough i was gonna ask about this too. i was reading recently on some haunted sites in japan, and re-read some theories on ghosts. i always assumed if they are real (i never had ANY supernatural experience in my life) that they would be purgatorial in nature. however, if not, it might be possible when people die they leave “ghost imprints” that re-enact their deaths or parts of their lives. only problem with the imprint theory is that most ghosts seem to interact, so they definitely have an intelligence of their own.
however if both are incorrect, let me propose one other theory i just thought up right now. most people are taught the idea of soul/spirit (spirit being yourself, “you”, and the soul being that which “animates” us (therefore we humans having both spirit/soul, animals it is assumed having only souls) now suppose on our deaths, when we depart, in some instances a “soul” copy is left here. Basically it is similar to the imprint theory, however it is one step beyond that because in this case, we have a copy of us left in this world, but it has a limited intelligence, like that of an animal, so it can be considered “living” (pardon the fact its a ghost) now notice how in most ghost cases, we have a wandering spirit which a: eventually disappear or fade out over time, whether it be decades or centuries and b: it has a single train of thought (its favorite spot to play, place of death, playing in the playroom, etc.) although some times it might do multiple tasks. also notice how spirits interact with people, but their actions are limited, like that of a household pet. basically my idea is that we leave, pardon it sounding rather odd, “soul copies”, which contain limited intelligence, have a limited lifespan, and can interact within a certain degree, and of course contain the strong emotions of that which, we, possesed. ok im gonna stop rambling now and let you guys tell me what you think about this idea.